Sludge centrifuge



SLUDGE CENTRIFUGE Filed Feb. 20, 1955 MN NN NR Q A m m f5 m n N my m.

INVENTOR Henrc Wilhelm Th BY e/wf/ L//efors United States Patent 3,237,854 SLUDGE CENTRIFUGE Henric Wilhelm Thylefors, Stockholm, Sweden, assignor to Aktiebolaget Separator, Stockholm, Sweden, a corporation of Sweden Filed Feb. 20, 1963, Ser. No. 259,957 Claims priority, application Sweden, Feb. 23, 1962, 2,006/ 62 2 Claims. (Cl. 233-20) The present invention relates to sludge centrifuges of the intermittently discharging type in which a lirst valve, hydraulically actuated in the axial direction of the rotor shaft, opens and closes sludge discharge openings located in the rotor wall and in which a second axially movable valve, when hydraulically actuated, opens disch-arge outlets for the operating liquid which actuates the irst valve.

A sludge centrifuge of this type is disclosed, for example, in Swedish Patent No. 178,744. In such a centrifuge, the operating liquids which `actuate both valves have a common outlet. The second valve is opened and maintained open by the pressure exerted by a liquid ring on one side of the valve against the action of springs, and the latter cannot close the valve before the pressure exerted by the liquid ring has dropped below a certain value. Thus, the time during which the first valve maintains the sludge discharge opening open will depend upon the time which elapses before the liquid pressure on one side of the second valve drops below this certain value. In some cases, however, it is desirable to reduce considerably the time during which the sludge discharge openings are kept open, particularly when it is required to discharge only comparatively small sludge quantities and only as little as possible of the liquid t-o be separated.

According to the present invention, this time reduction is obtained by an arangement in which the operating liquid for the -rst valve is discharged therefrom through openings leading outside the 4rotor entirely apart from .the chambers to which the operating liquid for opening the second valve is supplied. 1f .the closing force is suiiiciently high, the second Valve can close as soon as the latter chamber has been entirely or partially emptied of operating liquid, in spite of the continued outiiow of operating liquid from the discharge openings of the first valve.

The closing of the second valve can, like its opening, be effected by hydraulic action which is brought about by means of an operating liquid normally constituted by fresh water. However, in some instances, -as on ships where the consumption of fresh water must be economized, springs are advantageously used for closing the second valve.

According to another time-shortening measure, the discharge openings for the operating liquid for the second valve open directly into atmosphere outside the rotor,

so that no liquid cushions which could counteract the closing of the second valve are formed at these discharge openings.

The invention is described more in detail below, reference being made -to the attached dra-wing in which the single illustration is a vertical sectional view of part of a preferred form of the new centrifuge having a vertical axis of rotation.

In the drawings, reference numeral 1 designates the rotor body having a cover 2 and a locking ring 3 which secures the cover to the rotor body. Relatively large sludge discharge openings 4 are located in evenly spaced relationship along the periphery of rotor body 1. While the separation is in progress, these openings are kept closed by means of a conical valve disk 5 having an annular ridge 6 which makes sealing Contact against the "ice cover 2. Reference numeral 7 designates a conventional set of conical disks in separating space 9 of the rotor. The liquid to be separated is led into the separation chamber 9 by way of a s0-called distributor 8. The rotor is carried and driven by a vertical shaft 10. A liquid in the interspace 11 between the valve disk 5 and the bottom of the rotor body 1 generates, under the action of the centrifugal force, the axial power or upward thrust required for closing the valve disk. Ghannels 112 distributed along the rotor periphery are provided for the discharge of operating liquid from the chamber 11. These channels or discharge openings are closed by a ring-shaped valve 13 provided with .a number of pads 14 (such as nylon) corresponding to the number of the channels 12, each pad sealing a channel outlet. A plate 15, which supports peripherally-spaced compression springs 16, is fixed to the bottom of lthe rotor body 1. These springs urge the valve 13 upward into closing position.

The :shaft 10 -is surrounded by a stationary cylindrical body 17 provided with a vertical channel 18 to which is connected a supply pipe 19 for an operating liquid, such as water. The plate 15 is provided with a ringshaped chamber 20 into 'which the channel 18 opens and from which a channel 21 leads to the chamber 11. The chamber 20 is provided at the bottom with drainage holes 22 and communicates at the top, by way of an overflow outlet 23 and a channel 24, with a ring-shaped interspace 25 between the ring-shapedv valve `1-3 and the bottom of the rotor body 1. The ring-shaped valve 13 slides in liquid-tight relation against a cylindrical surface 26 on the bottom of the rotor body 1. The chamber 25 is further provided with drainage holes 27 arranged in the ringshaped Valve 13.

It will be understood that the rotor 1 is provided at its upper portion wit-h the usual outlet (not shown) for the liquid separated as the lighter component in separating chamber 9, the sepa-rated liquid being displaced inwardly from the spaces between discs 7.

In the oper-ation of the centrifuge, let it be assumed that rot-or 1 is being driven and that the centrifuging operation is in progress with valve disk 5 in its closed position. Water is supplied through the pipe 19 at such a low rate that the chamber 111 is kept iilled only .to the level determined by the holes 22 through which all the surplus water is ejected. When sludge is to be discharged from the centrifuge, the rate of supply of water 1through the pipe 19 is increased so that the liquid level in the chamber 20, in spite of the outflow through holes 22, is displaced radially inward whereby water flows ove-r the overflow outlet 23 and through the channel 24 into the chamber 25. When the liquid level in chamber 25 has increased sutiiciently inward, despite the outflow through the drainage holes 27, the liquid pressure in the chamber 25 (together with the liquid pressure against the pads 14) overcomes the closing power of .the springs 16 so that the valve 13 opens the channels 12. Water is then discharged from the chamber 11 through these channels, whereupon the valve disk 5 opens after the liquid level in chamber 11 has been displaced a certain distance outward. Sludge is then discharged through the openings 4. The supply of wat-er .through the pipe 19 is interrupted after a certain period of .time corresponding to the time during which it is desired that the openings 4 are maintained open. The chamber 25 is thus drained through the openings 27 and, at the same time, water continues t-o flow out through the channels 12. After the liquid level has decreased su'iciently in the chamber 25 (or this chamber has been completely drained) the springs 16 overcome the opposing force on the ring-shaped valve 13 and thus close this Valve before all the water in the chamber 11 has been discharged through the channels 12. The water remaining in the chamber 111 is then capable of closing the valve disk 5 before all the contents ofthe separation chamber 9 has been ejected through the openings 4. Water is .then supplied again through the pipe 19 in `such quantity that the chamber 11 is iilled to the level of the holes 22, so that the valve disk 5 is kept securely closed lagainst the increasing downward force exerted on it as the separation chamber 9 is reiilled with feed material from distributor 8.

It will be apparent that the parts 17 through 24 form in effect a liquid supply means for feeding an operating liquid .to the iirst chamber 11, such means being operable also to feed -operating liquid to the second chamber 25.

I clairn:

1. A sludge centrifuge comprising a centrifugal rotor mounted for rotation about an axis and having a separating space and also having a peripheral opening for discharging separated sludge from said space, a lirst valve in the rotor partly deiining said separating space and Vmovable axially of the rotor to open and close said sludge discharge opening, ysaid Valve forming with the rotor a first operating liquid chamber, the rotor having ta tirst operating liquid outlet leading from the outer portion of said tirst chamber to the outside of the rotor,

a second valve carried by the rotor and normally biased to a closed position for closing said iirst outlet, the second valve forming with the rotor .a second oper-ating liquid chamber and being movable axially of the rotor by liquid in vsaid second chamber to an open position for opening said first outlet, and liquid supply means communicating with said chambers for feeding operating liquid to said tirst chamber to move the Iirst valve into position for closing the sludge discharge opening, said means being operable to feed operating liquid t-o said second chamber to move the second valve to its open position for discharging liquid from said first chamber, said second chamber having an operating liquid outlet separate from said rst liquid outlet.

2. A sludge centrifuge according to claim 1, in which said liquid outlet from the second chamber opens directly into atmosphere outside the rotor.

References Cited lby the Examiner FOREIGN PATENTS 1,284,378 1/1962 France.

662,451 12/ 1951 Great Britain.

M. CARY NELSON, Primary Examiner. 

1. A SLUDGE CENTRIFUGE COMPRISING A CENTRIFUGAL ROTOR MOUNTED FOR ROTATION ABOUT AN AXIS AND HAVIG A SEPARATING SPACE AND ALSO HAVING A PERIPHERAL OPENING FOR DISCHARGING SEPARATED SLUDGE FROM SAID SPACE, A FIRST VALVE IN THE ROTOR PARTLY DEFINING SAID SEPARATING SPACE AND MOVABLE AXIALLY OF THE ROTOR TO OPEN AND CLOSE AND SLUDGE DISCHARGE OPENING, SAID VALVE FORMING WITH THE ROTOR A FIRST OPERATING LIQUID CHAMBER, THE ROTOR HAVING A FIRST OPERATING LIQUID OUTLET LEADING FROM THE OUTER PORTION OF SAID FIRST CHAMBER TO THE OUTSIDE OF THE ROTOR, A SECOND VALVE CARRIED BY THE ROTOR AND NORMALLY BIASED TO A CLOSED POSITION FOR CLOSING SAID FIRST OUTLET, THE SECOND VALVE FORMING WITH THE ROTOR A SECOND OPERATING LIQUID CHAMBER AND BEING MOVABLE AXIALLY OF THE ROTOR BY LIQUID IN SAID SECOND CHAMBER TO AN OPEN POSITION FOR OPENING SAID FIRST OUTLET, AND LIQUID SUPPLY MEANS COMMUNICATING WITH SAID CHAMBERS FOR FEEDING OPERATING LIQUID TO SAID FIRST CHAMBER TO MOVE THE FIRST VALVE INTO POSITION FOR CLOSING THE SLUDGE DISCHARGE OPENING, SAID MEANS BEING OPERABLE TO FEED OPERATING LIQUID TO SAID SECOND CHAMBER TO MOVE THE SECOND VALVE TO ITS OPEN POSITION FOR DISCHARGING LIQUID FROM SAID FIRST CHAMBER, SAID SECOND CHAMBER HAVING AN OPERATING LIQUID OUTLET SEPARATE FROM SAID FIRST LIQUID OUTLET. 